JSON数据的应用

版权声明：希望大家多多指教 https://blog.csdn.net/muriyue6/article/details/81166123

JSON数据的应用

什么是JSON

JSON是一种与开发语言无关的、轻量级的数据格式. 全称 JavaScript Object Notation.

优点: 易于人的阅读和编写, 易于程序解析与生产

标准的JSON数据表示

数据结构 - Object

使用花括号{}包含的键值对结构, Key必须是String类型, Value为任何基本类型或数据结构.

数据结构 - Array

使用中括号[] 来起始, 并用逗号来分隔元素

1、JsonObject封装JSON数据

 导入依赖:

<dependency>
 <groupId>org.json</groupId>
 <artifactId>json</artifactId>
</dependency>

package com.json;
import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;

/**
 *  封装JSON数据
 * Created by gailun on 2018/7/18.
 */
public class JsonObjectSample {
    public static void main(String[] args) {
        JSONObject();
        createJSONObject();
    }

    /**
     *  通过JSONObject对象封装JSON数据
     */
    private static void JSONObject(){
        JSONObject jsonObject = new JSONObject();
        Object nullObj = null;
        try {
            jsonObject.put("name","奋斗");
            jsonObject.put("age",26.8);
            jsonObject.put("birthday","1990-01-01");
            jsonObject.put("major",new String[]{"敲代码","微商"});
            jsonObject.put("girlfriend",false);
            jsonObject.put("house",nullObj);
            System.out.println(jsonObject.toString());
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    /**
     *  通过Map封装JSON数据
     */
    private static void createJSONObject(){
        Map<String,Object> jsonObject = new HashMap<>();
        jsonObject.put("name","奋斗");
        jsonObject.put("age",26.8);
        jsonObject.put("birthday","1990-01-01");
        jsonObject.put("major",new String[]{"敲代码","微商"});
        jsonObject.put("girlfriend",false);
        jsonObject.put("house",null);

        JSONObject jsonObject1 = new JSONObject(jsonObject);
        System.out.println(jsonObject1.toString());

    }

    //第三中方法是创建一个实体对象, 对象的属性值和map的Key相同,
    // 然后把对象的值封装到对象中, 最后把对象放到new JSONObject(对象)中
}

执行结果:

2、JsonObject解析JSON数据

json1文件(在resources目录下):

{
  "birthday": "1990-01-01",
  "girlfriend": false,
  "major": ["敲代码", "微商"],
  "name": "奋斗",
  "age": 26.8
}

package com.json;
import org.apache.commons.io.FileUtils;
import org.json.JSONArray;
import org.json.JSONObject;
import java.io.File;
import java.io.IOException;

/**
 *  解析JSON数据
 * Created by gailun on 2018/7/18.
 */
public class ReadJSONSample {
    public static void main(String[] args) throws IOException {
        File file = new File(ReadJSONSample.class.getResource("/json1").getFile());
        String content = FileUtils.readFileToString(file);
        JSONObject jsonObject = new JSONObject(content);
        if (!jsonObject.isNull("name")){
            System.out.println("姓名是:"+jsonObject.getString("name"));
        }
        System.out.println("年龄是: "+jsonObject.getDouble("age"));
        System.out.println("有没有女朋友: "+jsonObject.getBoolean("girlfriend"));
        JSONArray jsonArray = jsonObject.getJSONArray("major");
        for (int i = 0; i < jsonArray.length(); i++) {
            String o = (String)jsonArray.get(i);
            System.out.println("专业-"+(i+1)+o);
        }
    }
}

执行结果:

3、通过Gson封装JSON数据

导入依赖:

<dependency>
 <groupId>commons-io</groupId>
 <artifactId>commons-io</artifactId>
 <version>2.4</version>
</dependency>

<dependency>
 <groupId>com.google.code.gson</groupId>
 <artifactId>gson</artifactId>
 <version>2.4</version>
</dependency>

package com.json;
import com.google.gson.FieldNamingStrategy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.annotations.SerializedName;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by gailun on 2018/7/19.
 */
public class GsonGreateSamp {
    public static void main(String[] args) {
        Map<String,Object> jsonObject = new HashMap<>();
        jsonObject.put("name","奋斗");
        jsonObject.put("age",26.8);
        jsonObject.put("birthday","1990-01-01");
        jsonObject.put("major",new String[]{"敲代码","微商"});
        jsonObject.put("girlfriend",false);
        jsonObject.put("house",null);

        //@SerializedName("")
        //Gson gson = new Gson();
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.setPrettyPrinting();
        gsonBuilder.setFieldNamingStrategy(new FieldNamingStrategy() {
            @Override
            public String translateName(Field field) {
                if (field.getName().equals("name")){
                    return "NAME";
                }
                return field.getName();
            }
        });
        Gson gson = gsonBuilder.create();
        System.out.println(gson.toJson(jsonObject));
    }
}

执行结果:

4、通过Gson解析JSON数据

json1文件(在resources目录下):

{
  "birthday": "1990-01-01",
  "girlfriend": false,
  "major": ["敲代码", "微商"],
  "name": "奋斗",
  "age": 26.8
}

package com.json;

import java.util.Date;
import java.util.List;

/**
 * Created by gailun on 2018/7/19.
 */
public class DemoWithBirthday {
    private String name;
    private double age;
    private boolean girlfriend;
    private Object house;
    private Date birthday;
    private List<String> major;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getAge() {
        return age;
    }

    public void setAge(double age) {
        this.age = age;
    }

    public boolean isGirlfriend() {
        return girlfriend;
    }

    public void setGirlfriend(boolean girlfriend) {
        this.girlfriend = girlfriend;
    }

    public Object getHouse() {
        return house;
    }

    public void setHouse(Object house) {
        this.house = house;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public List<String> getMajor() {
        return major;
    }

    public void setMajor(List<String> major) {
        this.major = major;
    }

    @Override
    public String toString() {
        return "DemoWithBirthday{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", girlfriend=" + girlfriend +
                ", house=" + house +
                ", birthday=" + birthday +
                ", major=" + major +
                '}';
    }
}

package com.json;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.util.Map;

/**
 * Created by gailun on 2018/7/19.
 */
public class GsonReadSample {
    public static void main(String[] args) throws IOException {
        File file = new File(ReadJSONSample.class.getResource("/json1").getFile());
        String content = FileUtils.readFileToString(file);

        Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
        DemoWithBirthday demoWithBirthday = gson.fromJson(content, DemoWithBirthday.class);
        System.out.println(demoWithBirthday);

        Gson gson1 = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
        Map map = gson1.fromJson(content, Map.class);
        System.out.println(map);
    }
}
执行结果:

5、通过Fastjson封装JSON数据

依赖为:

<dependency>
 <groupId>com.alibaba</groupId>
 <artifactId>fastjson</artifactId>
 <version>1.2.29</version>
</dependency>

package com.json;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by gailun on 2018/7/23.
 */
public class FastjsonGreateSample {
    public static void main(String[] args) {
        Map<String,Object> jsonObject = new HashMap<>();
        jsonObject.put("name","奋斗");
        jsonObject.put("age",26.8);
        jsonObject.put("birthday",new Date());
        jsonObject.put("major",new String[]{"敲代码","微商"});
        jsonObject.put("girlfriend",false);
        jsonObject.put("house",null);

        //将Map转成JSON
        String string = JSON.toJSONString(jsonObject);
        System.out.println(string);

        //FastJSON将java.util.Date转成long
        String st = JSON.toJSONString(new Date());
        System.out.println(st);

        //使用SerializerFeature特性格式化日期
        String dateJson = JSON.toJSONString(new Date(), SerializerFeature.WriteDateUseDateFormat);
        System.out.println(dateJson);

        //指定输出日期格式
        String dateJson1 = JSON.toJSONStringWithDateFormat(new Date(), "yyyy-MM-dd HH:mm:ss");
        System.out.println(dateJson1);

    }
}

执行结果:

6、通过Fastjson解析JSON数据

package com.json;
import com.alibaba.fastjson.JSON;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.util.Map;

/**
 * Created by gailun on 2018/7/23.
 */
public class FastjsonReadSample {
    public static void main(String[] args) throws IOException {
        File file = new File(ReadJSONSample.class.getResource("/json1").getFile());
        String content = FileUtils.readFileToString(file);

        Map map = JSON.parseObject(content, Map.class);
        System.out.println(map);
    }
}

执行结果: